1. Field of the Invention
The invention relates to a treatment method of a semiconductor wafer (hereinafter referred to as wafer), which is especially useful as a treatment method applied to a process including a step of adhering a dicing sheet to the wafer, following a grinding step for thinning the wafer (or one of various kinds of polishing steps) after circuits are formed on the wafer; and to an apparatus using the treatment method of the wafer.
2. Prior Art
A semiconductor wafer made of silicon, gallium, arsenide or the like has been conventionally used in a way such that circuits are formed on the wafer, thereafter a grinding step for thinning the wafer is applied thereto, then a dicing sheet is adhered thereto and the wafer with the sheet is then diced into small device pieces, followed by a mounting step (see, for example, JP-A No. 2003-7646). In such a process, since steps including as far as polishing or back grinding of a back surface of a wafer after a pattern forming process thereon have been regarded as the front-end process in semiconductor fabrication, the back grinding step is separated from a step of adhering a dicing sheet to the back surface of a wafer; therefore, it has been common that one day or longer passes till the dicing sheet is adhered to the wafer after the end of polishing or back grinding.
The wafer polishing step, however, has been regarded as the back-end process in recent years. And a dicing sheet is adhered within a few hours of the end of polishing, or alternatively, a process from a wafer polishing apparatus to the dicing sheet adhering apparatus is integrated into a single system; therefore, cases increase where a dicing sheet is adhered to the wafer immediately after the end of polishing.
In a case where, in this way, a dicing sheet is adhered to a wafer a few hours after the end of polishing, or a process from a wafer polishing apparatus to a dicing sheet adhering apparatus is integrated into a single system, so a dicing sheet is adhered to the wafer immediately after the end of polishing, a sticking force between the dicing sheet and the back surface of a wafer increases, which has led to a possibility to cause a problem that when semiconductor chips obtained by being separated into small pieces are picked up after the dicing step, the picking-up is disabled or contamination by the dicing sheet is severe even if the picking-up is enabled.